The tree stump grinder drum drive is an improvement in the tree stump grinder disclosed in my U.S. Pat. No. 5,158,126 issued Oct. 27, 1992, the disclosure of which is incorporated herein by reference.
The stump grinder drum is rotatably mounted on the boom of an excavator or a backhoe. The excavator or backhoe transport the drum to the site where a tree stump is to be ground. The boom on the excavator moves the drum into contact with a tree stump or a tree root. A hydraulic motor rotates the drum so that the bits on the outer surface of the drum grind up the tree stump and tree roots. The tree stump and tree roots are ground up into chips in the area where the tree grew. The wood chips improve the fertility of the soil. By grinding tree stumps and tree roots into wood chips where they grew, it is possible to eliminate removal, transport and disposal problems. The tree stumps are anchored and held by their roots during the early stages of the grinding operation. The grinder drum moves soil and rocks near the tree stumps and tree roots during grinding, thereby permitting the grinder drum to grind up all of a tree stump and all of the larger roots.
The excavator or backhoe which the grinder drum is mounted on is preferably a relatively large heavy machine. The excavator or backhoe can transfer several tons of its total weight to the grinder drum to increase grinding speed or it can hydraulically squeeze a tree stump between the grinder drum and an anchor assembly thereby placing an even larger load on the grinder drum. A hydraulic motor is mounted inside the drum. A hydraulic pump driven by a diesel engine supplies hydraulic fluid to the hydraulic motor under pressure. It is preferable to provide a second diesel engine with over 250 horsepower that drives the hydraulic pump for the grinder drum only. The excavator engine may have insufficient power to operate the excavator and to drive the stump grinder drum at the same time.
The grinder drum must be supported by large bearings that can withstand the large radial loads that may be applied to the grinder drum. The grinder drum also has to withstand axial loads that tend to deflect the drum end plates. The hydraulic motor which drives the drum must be sufficiently large to provide the required torque, compact to fit inside the grinder drum and long lasting. The bearings which support the grinder drum must be adequately lubricated and sealed. The seals must keep lubricant in and keep foreign material such as dirt, sand, rocks, water, roots and wire out.